The present disclosure relates to cementing operations in subterranean drilling. More particularly, the present disclosure relates to an apparatus and method for installing a cement head on borehole casing.
In oil and gas drilling, a casing is placed inside the open borehole to maintain borehole stability and to control formation pressures. In many of these boreholes, an intermediate casing is installed and cemented into place. After the intermediate casing is installed, drilling can be continued through this casing to a deeper depth. Formations outside the intermediate casing are thus isolated, which helps to eliminate borehole cave-in and helps to contain formation pressures and fluids.
To cement the casing into a drilled borehole, a cement head is installed on the casing. The cement head contains hoses and piping to transfer cement and water from pumps to the inside of the casing. The cement head also contains valves to launch a rubber wiper plug down inside the casing. Once the cement head is installed on the casing, a pre-calculated volume of cement is pumped into the cement head, down the inside of the casing, and up the outside of the casing to the surface. Once the cement is pumped inside the casing, the rubber wiper plug is installed inside the casing on top of the cement slurry. Water is then pumped inside the casing to push the wiper plug downwards and thereby displace the cement slurry from the inside of the casing to the outside of the casing. Once adequate time has expired for cement curing, the plug can be drilled out and drilling to deeper depths can continue.
In many cases, cement heads must be positioned high above the rig floor during cementing operations. Installing a cement head on the case in such instances generally requires a crane or winch to raise the cement head to the case. Frequently, personnel must be hoisted off the rig floor using a makeshift seat or harness attached to a winch or other lifting device in order to reach the cement head and case to connect the cement head to the case. In addition to connecting the cement head to the case, the personnel attach pipes and pipe fittings to the cement head to connect the cement head to pumps located on the ground. Such personnel are at risk of falling. Moreover, such personnel are frequently required to carry heavy bars, wrenches and other tools used to manipulate both the cement head and the pipes and fittings that they attach to the cement head. These bars, wrenches and other heavy tools are at risk of being accidentally dropped onto the rig floor below.